﻿#region License
/*
MIT License
Copyright Â© 2006 The Mono.Xna Team

All rights reserved.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
*/
#endregion License

using System;

namespace VpNet
{
    public static class MathHelper
    {
        public const double E = (double)Math.E;
        public const double Log10E = 0.4342945f;
        public const double Log2E = 1.442695f;
        public const double Pi = (double)Math.PI;
        public const double PiOver2 = (double)(Math.PI / 2.0);
        public const double PiOver4 = (double)(Math.PI / 4.0);
        public const double TwoPi = (double)(Math.PI * 2.0);

        public static double Barycentric(double value1, double value2, double value3, double amount1, double amount2)
        {
            return value1 + (value2 - value1) * amount1 + (value3 - value1) * amount2;
        }

        public static double CatmullRom(double value1, double value2, double value3, double value4, double amount)
        {
            // Using formula from http://www.mvps.org/directx/articles/catmull/
            // Internally using doubles not to lose precission
            double amountSquared = amount * amount;
            double amountCubed = amountSquared * amount;
            return (double)(0.5f * (2.0f * value2 +
                (value3 - value1) * amount +
                (2.0f * value1 - 5.0f * value2 + 4.0f * value3 - value4) * amountSquared +
                (3.0f * value2 - value1 - 3.0f * value3 + value4) * amountCubed));
        }

        public static double Clamp(double value, double min, double max)
        {
            return value > max ? max : (value < min ? min : value);
        }

        public static double Distance(double value1, double value2)
        {
            return Math.Abs(value1 - value2);
        }

        public static double Hermite(double value1, double tangent1, double value2, double tangent2, double amount)
        {
            // All transformed to double not to lose precission
            // Otherwise, for high numbers of param:amount the result is NaN instead of Infinity
            double v1 = value1, v2 = value2, t1 = tangent1, t2 = tangent2, s = amount, result;
            double sCubed = s * s * s;
            double sSquared = s * s;

            if (amount == 0f)
                result = value1;
            else if (amount == 1f)
                result = value2;
            else
                result = (2.0f * v1 - 2.0f * v2 + t2 + t1) * sCubed +
                    (3.0f * v2 - 3.0f * v1 - 2.0f * t1 - t2) * sSquared +
                    t1 * s +
                    v1;
            return (double)result;
        }


        public static double Lerp(double value1, double value2, double amount)
        {
            return value1 + (value2 - value1) * amount;
        }

        public static double Max(double value1, double value2)
        {
            return Math.Max(value1, value2);
        }

        public static double Min(double value1, double value2)
        {
            return Math.Min(value1, value2);
        }

        public static double SmoothStep(double value1, double value2, double amount)
        {
            // It is expected that 0 < amount < 1
            // If amount < 0, return value1
            // If amount > 1, return value2
            double result = MathHelper.Clamp(amount, 0f, 1f);
            result = MathHelper.Hermite(value1, 0f, value2, 0f, result);
            return result;
        }

        public static double ToDegrees(double radians)
        {
            // This method uses double precission internally,
            // though it returns single double
            // Factor = 180 / pi
            return (double)(radians * 57.295779513082320876798154814105);
        }

        public static double ToRadians(double degrees)
        {
            // This method uses double precission internally,
            // though it returns single double
            // Factor = pi / 180
            return (double)(degrees * 0.017453292519943295769236907684886);
        }


        public static double WrapAngle(double angle)
        {
            angle = (double)Math.IEEERemainder((double)angle, 6.2831854820251465); //2xPi precission is double
            if (angle <= -3.141593f)
            {
                angle += 6.283185f;
                return angle;
            }
            if (angle > 3.141593f)
            {
                angle -= 6.283185f;
            }
            return angle;
        }

    }
}